Compliments of Doppelganger who found this article on samba forum and thought it might be of interest to some of you as its meant to help answer some of the VW transmission questions.

Identifying VW Transaxles...

The 091...Aka the 6-rib
Found in '76-'79 Bus. They have a 4.56 R&P ratio, and are considered to be the strongest stock VW transmission.

091-Side Shift
*Note: This is the one that can be converted to nose shift.
Essentially the same as the Bus 091 and can be converted to nose shift.
Found in '80-'83 Vanagons with the T4 engine.

091-Mid Shift
*Note: This one cannot be converted to nose shift.
This may actually be an 094 instead of an 091, but I haven't verified this yet.
Found in '83-up Vanagons with the Wasserboxer engine.

094 Synchro 4x4
*Note: I don't know much about this one, except for the fact that they are pretty rare. However, they have a locking differential that can be made to fit in an 091 or 002 (More on this later).
Found in ??-?? Synchro Vanagons.

The 002...Aka the 3-rib
*Note: The earlier 3-ribs have no mounting ears on top of the bellhousing, axle flange retainers attached by acorn nuts, and a shorter input shaft (for the T1 engine). There's more info the early models posted below the pic. They have a 5.38 (Also 5.42, but it is pretty rare) R&P ratio.

Quote:

The first Bus IRS trans in 68 is called a 113 type Bus trans. Same for those up to 71. This is because all the parts associated with the 4 forward gears and reverse are exactly the same as what are found in a Beetle 113 trans. Exceptions are gear ratios and tooth configuration.

Then in 72, the 002 Bus trans came out. The individual gears were all completely re-designed and are called 002 gears. These were used to the end of 75. Beetle gearboxes with only one side cover also use the exact same 002 Bus type gears.

The 002 5-rib
*Note: Even though the 5-rib has a few different components than the 3-rib, it's still classified as a 002.
Found in '74-'75 Bus. They have a 4.86 R&P ratio.

Vanagon Diesel
No information available at this time.

Bug IRS-Late
*Note: The one on the left is from '75-up, and the one on the right is from '72-'74. As far as I know they are the same except for the case differences.
Found in the '72-up Bug. They have a 3.88 R&P ratio.